Formation of tube bends



Jan. 10, 1961 A. HUET FORMATION OF TUBE BENDS Filed Nov. 20, 1956 INVENTOR HNDIZE HUE'T FIG. 4

L w T v w FORMATION OF TUBE BENDS Andr Huet, Paris, France, assignor to Combustion Engineering, Inc., New York, N.Y., a corporation of Delaware Filed Nov. 20, 1956, Ser. No. 623,413

Claims priority, application France Nov. 23, 1955 2 Claims. (Cl. 29-157) The present invention relates to metal working, particularly to tube working and specifically to formation of a bend or bifurcate with an offset branch.

It is possible to produce, as by forging, a 180 tube bend having in the axis of symmetry of the bend a joint or extension tube, which constitutes a bend with a centered neck. To obtain such bends with centered neck it is possible to first fashion an offset bulb on a straight tube by axial compression of this tube in a matrix and then bend the tube, thus bulbed, so as to obtain a bulb in the axis of the bend, which bulb may then be opened to constitute a neck or tubular neck; also by starting with a large radius tube bend and then compressing this bend between matrices so as to obtain, in the axis of the bend, a bulb which is opened at some stage of the compression to constitute the neck or tube connection. Finally, the two processes above, which are facilitated by a judicious heating of certain regions in the piece to be heated, canbe combined.

The subject of the present invention is the fabrication of a bend with an offset tube connection or neck, that is to say one in which the neck, instead of being in the axis of symmetry of the 180 bend, is offset in such a way that its axis comes close to that of one of the straight tube legs of the bend.

Applicant has found that it was possible to fashion, in an unexpected manner, such elbows with offset neck by compressing a tube bend with centered neck between asymmetric matrices, in combination with asymmetrical preliminary heating of the initial elbow.

The following description when read with regard to the accompanying drawings will make understood how the invention can be practiced.

Figure 1 is a section of a 180 bend with centered neck from which applicant forms the offset tube bend.

Figure 2 is a section of the bend in Figure 1 disposed between two asymmetrical matrices.

Figure 3 is a view similar to Figure 2 after the matrices have been brought together.

Figure 4 is an end view of Figure 3 from the side of the tube.

Figure 5 is an end view of the otiset-tube bend, after shaping of the tube.

Figure 6 is a section through 6-6 of Figure 3.

As said above, according to the present invention one starts with a 180 bend 10, with centered neck 12, that is to say a neck disposed in the axis of symmetry xx of the bend (Figure 1). According to the present invention the bend 10 is heated, for example to cherry red, in the region of the bend, hachured in Figure 1, bringing to about white heat half of this heated region, which is situated on the side where the off center neck is desired, that is to say the cross-hatched region at the right of Figure 1, on the side of the straight branch 14 of the bend. This done, the bend 10 is placed in a compression machine with the straight arms 14, 16 of the bend parallel to each other, the machine being constituted by two tates P tent matrices 20, 22 which can be brought together by a movement of translation between two plates 24, 26 (Figure 4). The matrix 20 which is applied to the arm 16 of the bend 10 (Figures 2 and 3) comprises a semi-cylindrical throat whose contour 21 is adapted to the final form which we want for the bend, on the side of the straight arm 16. Contrariwise, the other matrix 22, also comprising a semicylindrical throat, and adapted to the straight arm 14 of the bend has a straight bottom 23 as seen in Figure 2.

Between the straight arms 14, 16 there is disposed a spread bar 28 designed to constitute the final stop when the two arms 14, 16 are brought together, and which comprises two half throats 30, 32 (Figure 6), to enclose the straight arms of the bend. This bar 28 ends in an asymmetrical contour 33 which corresponds to the final curve of the inside region of the bend wanted. The bar 28 is preferably floating during the operation that brings the matrices 20 and 22 together so that it may, of itself, assume the desired position during the approach of the matrices, according to whether one or the other arm 14, 16 is the first to come into contact with the said bar 28.

At the beginning of the operation of compression as seen in Figure 2, the matrix 20 comes over the outside bend region where tube 12 begins and located on the left of Figure 2, while the straight matrix 22 applies on the straight arm 14 of the bend. The two matrices 20 and 22 are then brought together in the direction of arrows A (Figure 2) and produce a compression of the bend as shown in Figure 3. In the course of the approach the tube 10 rises slightly on the left of Figure 2 while as seen on the right side of Figure 3 the straight arm 14 of the bend is applied against the bar 28. The result is that the bent region of the tube 12 on the right is shaped, and the metal in the tube rises, as we see at 40. The priming of the neck 12 thus obtained during the compression is, as we see in Figure 4 offset with respect to the axis x-x of the original bend which is projected at X in Figure 4, and the said neck 12 has been brought closer to the axis of the straight arm 14,

It is then sufficient, thanks to the quantity of metal which we have on the blank of neck 12, to expand and shape the section of the said neck to finally obtain the band with offset neck 12 which we see in end view in Figure 5. The diameter of the final neck 12 can be much larger than the diameter of the straight branches 14, 16 of the bend. By way of example, for an inside arm diameter of 60 mm., we may have an inside tube diameter of mm.

Of course, modifications of detail can be imparted to the embodiment of this invention without thereby departing from its scope. Thus the straight matrix 22, instead of having a bottom 23 parallel to the straight arms 14, 16 of the bend, may have a base inclined to the axis of these arms and may begin during the compression by pressing on the bent region of the bend which would have the eflfect of accentuating the flattening movement towards the bottom of the arm 14 of the bend against the bar 28.

What is claimed is:

l. The process of fabrication of a bend with offset neck red heat while heating the side of the bend towards which the neck is to be offset to white heat; compressing the said bend between two asymmetrical matrices, one of which has a throat with base shaped to a half of the final bend desired, while the other has a straight base pressing on the tube leg of the bend towards which the neck is to be offset with said throat leading to a cavity or sink conforming substantially to the straight leg portion of the bend with a projection or land 2 offset toward said throat for l engaging said neck prior to engagement of said sink with said leg portion; and disposing a separation bar forming an end-of-movement stop between the tube legs of the bend and which bar has a shape conforming to the crotch and contiguous straight leg portion of the-desired bend and, preferably, floats between these tube legs during the operation of compression.

2. The method of fabricating a tubular bifurcate having an offset tubular neck comprising the steps of forming a return bend having tubular legs merging into the crotch region with an open neck portion projecting from the elbow of the bend opposite the crotch and symmetrically located with respect to the longitudinal axes of the tube legs; heating the elbow portion at one side of the longitudinal axis of symmetry of the bend that is alined with and merges into one tube leg to white heat and the elbow portion merging into the other tube leg to red heat; applying oppositely directed compressive forces acting normal to the longitudinal axes of the bend against both tube legs to reduce the spacing of the tube legs while confining the bend in a die having a cavity formed to olfset the tube legs and displace the neck portion on the elbow from the plane of symmetry of the bend in a direction toward the axis of the more intensely heated tube leg, the die cavity having an open throat for accommodating the neck on the elbow and permitting heated metal of the bend to flow into the cavity to enlarge the neck, with said throat leading to a cavity or sink conforming substantially to the straight leg portion of the bend with a projection or land oflset toward said throat for engaging said neck prior to engagement of said sink with said leg portion.

References Cited in the file of this patent UNiTED STATES PATENTS 2,689,596 H1161: Sept. 21, 1954 2,830,645 Huet Apr. 15, 1958 FOREIGN PATENTS 1,107,216 France Dec. 29, i955 

